Melatonin

Melatonin is one of the most misunderstood things sold in a drugstore, and the misunderstanding got there with help from the supplement industry, the pediatrician’s office, and your uncle who knows a guy. People take it the way they’d take Benadryl, like a sedative, like a thing that knocks you out. That isn’t what it does. It’s a circadian signal, the chemical your pineal gland (a tiny gland in the middle of your brain that runs the body clock) makes in tiny amounts as the light dies down in the evening, and the signal it sends to the rest of your brain is roughly: it’s getting to be nighttime, start winding things down.

That’s the whole job. It doesn’t sedate you, it doesn’t depress your breathing, it doesn’t even bind at GABA receptors (the system real sleeping pills hit). It tells the master clock in your hypothalamus what time it is. If your clock is already on time and you’re just tossing because of stress, caffeine, or your kid woke up at 3 AM, melatonin isn’t going to do much for you. If your clock is genuinely shifted, melatonin can be one of the most useful things in the cabinet.

The other piece nobody talks about is the dose on the bottle. The 5mg gummy at CVS, the 10mg “extra strength” at Costco, the 12mg sleep stack from whatever Instagram brand your buddy at the gym swears by. Your own pineal gland produces something on the order of 0.1 to 0.3mg at peak. Pharmacologic doses don’t make the signal louder in a useful way, they flood the receptors, cause downregulation (meaning your own system makes less of it because the receptors are saturated), give you weird dreams, and leave you groggy at 9 AM. More is genuinely worse, which is not how anybody markets it.

More is genuinely worse, which is not how anybody markets it.

The four situations where it earns its keep

Four specific situations, in roughly the order of how well the data holds up.

Jet lag. You flew from New York to Paris and your body still thinks it’s 6 PM when the Parisians are going to bed. A small dose of melatonin a few hours before local bedtime for two or three nights helps drag your circadian rhythm forward. This is the use case where the evidence is cleanest and the effect is easiest to feel, and it’s basically what the drug exists for.

Delayed sleep phase syndrome. The teenager or twenty-something whose body genuinely doesn’t want to sleep until 3 AM and doesn’t want to wake until 11. This is an actual circadian phenotype, separate from being lazy or being on a phone too long, and a real chunk of the population runs naturally that way. Small-dose melatonin given several hours before the target bedtime, paired with morning bright light, can shift the whole rhythm earlier over a few weeks. It’s slow, you have to be consistent, and it works.

Shift work, occasionally, in patients who are stuck on rotating schedules and need to convince their brain that 10 AM is bedtime. Never a clean fix because the rest of the world is loud at 10 AM and the sun is doing the opposite of what you’d want it to, but it can take the edge off if you stack it with blackout curtains and consistency.

REM sleep behavior disorder. This one sits in its own category. RBD is the disorder where people physically act out their dreams, punching, kicking, falling out of bed. It tends to show up in older men and it’s an important neurological finding because it predicts Parkinson’s disease and Lewy body dementia downstream, which is the kind of thing that wakes you up faster than a punch from a sleeping spouse. Melatonin at moderate doses, 3 to 6mg at bedtime, reduces the muscle activity during REM sleep and lets the bed partner sleep without getting punched. Clonazepam used to be first-line for RBD. Melatonin has quietly displaced it in a lot of sleep clinics because the side-effect profile is better.

The dose on the bottle is wrong for almost everybody buying it, and the supplement industry has spent two decades getting people to take more of it instead of less, which is great for sales and bad for sleep.

Where the marketing falls apart

Chronic insomnia in middle-aged adults. The kind of patient who can’t fall asleep because his brain is still finishing tomorrow’s meeting at midnight. His circadian rhythm is fine. The problem is hyperarousal (the part of the nervous system that’s supposed to slow down at night just keeps idling at higher RPMs), and melatonin doesn’t touch hyperarousal. He’ll come back in three weeks frustrated that the bottle he spent $24 on at Whole Foods didn’t help. What helps him is CBT-I (cognitive behavioral therapy for insomnia, the structured sleep-restriction-and-stimulus-control kind), maybe a low-dose trazodone, sleep restriction, getting caffeine out after noon.

Anxiety. There’s a tiny anti-anxiety effect at the receptor level that some studies have chased, but in practice nobody should be using melatonin for anxiety. It doesn’t reach a useful dose for that purpose, and there are actual anti-anxiety medications if anxiety is what’s going on.

Kids who won’t fall asleep. This is the use case where I’ve got the strongest opinion and the smallest amount of grace. Parents are giving toddlers melatonin gummies because the pediatrician’s office mentioned it in passing or a friend in the group chat said it worked for her kid. Melatonin in kids isn’t well studied long-term, and what little we have isn’t reassuring. It’s an active hormone with effects on reproductive timing in animal studies. The kid who can’t fall asleep almost always has a behavioral or environmental reason… screens in the bedroom, no consistent bedtime routine, a 6 PM nap, mom and dad letting the kid stay up because they’re tired too. Fix the environment before you medicate the child with a hormone we don’t fully understand the developmental effects of.

Say you’ve got a parent who walks in with a kid who’s been on 5mg of melatonin nightly for a year or two, and the kid is waking at 4 AM every morning wired, because pharmacologic melatonin in a child produces a long tail that disrupts sleep architecture downstream. Pull the melatonin over ten days, tighten up the bedtime routine, kill the screen at 7 PM, and three weeks later the kid is sleeping through the night on nothing. Not to be Chicken Little about it, but this story plays out constantly, and the supplement industry has zero incentive to surface it.

Timing matters more than dose

Take melatonin at bedtime and you’re using it as a sedative, which it does poorly. Take it three to five hours before your desired bedtime and you’re using it as a phase shifter, which is what it actually does. For a delayed-phase patient trying to fall asleep at 11 PM instead of 2 AM, that means dosing around 6 or 7 PM, not at 10:45 while brushing teeth.

Dose of 0.3 to 1mg is what the chronobiology labs use. You can usually find 0.5mg or 1mg tablets if you actually look. The 3mg version is the smallest dose most US retailers carry, which is already higher than what produces the cleanest phase shift. The 5mg and 10mg gummies that dominate the shelves are pharmacologic doses being marketed as if more were better, they produce blood levels that hang around into the morning and leave you groggy. There’s no scenario where the high-dose gummy is doing what the label implies, and there’s a real scenario where it’s the reason you feel like garbage tomorrow.

The supplement industry mess

Melatonin is sold as a dietary supplement in the US, which means it doesn’t go through the FDA approval process and the dose on the bottle is whatever the manufacturer decided to print. A study published in JAMA in 2023 tested 25 melatonin gummy products and found actual melatonin content ranging from 74 percent to 347 percent of what the label claimed, with 88 percent of them inaccurately labeled. One product contained no detectable melatonin at all, just 31mg of CBD. That isn’t a one-off, that’s the regulatory landscape on the gummies sitting on the shelf at the grocery store.

If you’re going to use it, get a brand with USP verification on the label, which means a third party has actually tested what’s in the bottle. That cuts out most of the worst offenders. Anyone selling you a 10mg “sleep stack” gummy on Instagram is, to put it bluntly, working a deregulated market that lets them put roughly whatever they want in the bottle, and the FDA isn’t coming to save you on the dietary supplement side. And if your pharmacy can compound a 0.5mg tablet, that’s probably more useful than anything you’ll find on a shelf.

How I actually think about it

Melatonin is a niche tool, useful for jet lag, useful for genuinely delayed-phase patients, useful for RBD, occasionally useful for shift work… and for most of the folks who walk in complaining about sleep, it isn’t the answer, and a lot of them have already been taking it for months at the wrong dose at the wrong time and getting nothing from it except weird dreams. When I take it off the table I usually have to explain why for fifteen minutes, because the cultural assumption that melatonin is a sleep aid is deep and the supplement industry has spent two decades reinforcing it.

The patient-autonomy piece works the same way here as anywhere. If you’ve heard the take and you still want to take 10mg every night, you’re going to. I’m a provider, not a parent, and melatonin doesn’t require my permission anyway. My job is the honest version of what it does and doesn’t do, so when you go pick out a bottle at Costco you’re at least picking with eyes open instead of buying into the marketing. The actual playbook, if you want one: small dose, right time of evening, paired with morning light if there’s a real circadian shift to chase, used for a finite stretch and not indefinitely. Almost nobody arrives running it that way, which is how a perfectly useful hormone got turned into another supplement that mostly doesn’t do anything.

Sources

1. Auld F, Maschauer EL, Morrison I, Skene DJ, Riha RL. Evidence for the efficacy of melatonin in the treatment of primary adult sleep disorders. Sleep Med Rev. 2017;34:10-22. PMID 28648359.
2. Costello RB, Lentino CV, Boyd CC, et al. The effectiveness of melatonin for promoting healthy sleep: a rapid evidence assessment of the literature. Nutr J. 2014;13:106. PMID 25380732.
3. Sateia MJ, Buysse DJ, Krystal AD, et al. Clinical Practice Guideline for the Pharmacologic Treatment of Chronic Insomnia in Adults: An American Academy of Sleep Medicine Clinical Practice Guideline, J Clin Sleep Med, 2017;13(2):307-349. PMID 27998379.
4. Herxheimer A, Petrie KJ. Melatonin for the prevention and treatment of jet lag, Cochrane Database Syst Rev, 2002;(2):CD001520. PMID 12076414.
5. Cohen PA, Avula B, Wang YH, Katragunta K, Khan I. Quantity of Melatonin and CBD in Melatonin Gummies Sold in the US, JAMA, 2023;329(16):1401-1402. PMID 37097362.